The effectiveness of electrostatic air cleaners installed in residential heating and cooling systems is well recognized and appreciated particularly by those bothered by allergenic air pollutants. However, the relatively high cost and objectionable 0.sup.3 generation of units having adequate capacity has in the past deterred wider use of these air cleaners in residences. While substantial design improvement, minimization of 0.sup.3 accumulation and reduction of construction cost of the electrostatic air cleaner have been made, the cost of installation particularly in existing residential heating and cooling systems has not decreased.
Less expensive, relatively easy to install electrostatic air cleaners of less than adequate capacity for the average size residence are presently commercially available. These air cleaners are dimensioned to replace the conventional one inch thick fiber glass filter usually positioned in a furnace or return air duct and are of single stage construction an example being the air cleaner disclosed in U.S. Pat. No. 3,763,633 to C. W. Soltis and shown on page 696 of a W. W. Granger Inc. catalog. In the Granger air cleaner the power supply may be interconnected with the furnace blower motor so that it is energized only when air is being circulated thereby to preclude accumulation of 0.sup.3 during the blower off cycle. Such interconnection however is required to be made by a licensed electrician and therefore substantially increases installation cost.
A larger capacity two-stage electrostatic air cleaner is shown on page 697 of the same Granger catalog sheet. This larger electrostatic cell with its attached high voltage power supply is relatively heavy and requires substantial and costly modification of an existing air return duct for its positioning and support therein as is shown in FIGS. 1 and 2 of U.S. Pat. No. 3,989,486.